It is well known in the prior art that wherein the flow of hydraulic fluid is controlled by a mechanism that failure sometimes occurs through the result of control valve seizure. When such occurs the flow of hydraulic fluid to a load or to a load-control mechanism is inconsistent with the command signals applied to the system in the first instance. Such improper load control can, under some circumstances, cause a failure of an entire mission dependent upon the control system. Various apparatus have been developed to overcome such spool seizure by way of utilization of bypass valves and the like. In all instances known to applicant, the seizure-developed signal is momentary in nature and may permit the system to continue to operate once a spool valve seizure has occurred. The prior art known to applicant is shown in U.S. Pat. Nos. 2,389,274; 2,940,428; 2,941,515; 3,213,886; 3,253,613; 3,338,138; 3,406,721; 3,426,792; 3,552,433; 3,555,969; 3,561,322; 3,570,516; 3,693,506; 3,702,575; 3,826,174; 3,908,515; 3,951,162; 4,009,642; 4,041,842; 4,138,088; 4,333,387; 4,394,999; 4,456,031; 4,555,976; 4,570,672.